More likely these guys were asleep somewhere when they should have been on duty. They’d likely gotten away with this behavior without any problem... right up until there was a problem. I mean really, what is the likelyhood of them being on a break the very moment this shooter shows up. It’s about as likely as the IRS randomly selecting Sara Palin’s dad for an audit.
Maybe the officers were bribed or distracted, so as to be on break at the opportune time?